Dictionary Form & Stem辞書形・語幹
The dictionary form (辞書形 jisho-kei) is the base form you find in dictionaries. It’s also the plain non-past affirmative form used in casual speech. Every other conjugation is built from this form, making it the foundation of the entire verb system. Understanding how to extract the stem from each verb group unlocks every conjugation in Japanese.
The dictionary form (辞書形 jisho-kei) is the base form you find in dictionaries. It’s also the plain non-past affirmative form used in casual speech. Every other conjugation is built from this form, making it the foundation of the entire verb system. Understanding how to extract the stem from each verb group unlocks every conjugation in Japanese.
What is the dictionary form?
The dictionary form is the "default" form of a Japanese verb. It has two roles: (1) it’s the citation form used in dictionaries, and (2) it functions as the plain non-past affirmative in casual speech. When a Japanese friend says 今日ラーメン食べる (kyou raamen taberu), they’re using the dictionary form directly. In formal writing and polite speech, you’d use the masu form instead (食べます), but the dictionary form is what all other conjugations are built from.
How to extract the verb stem
The stem (語幹 gokan) is the part of the verb that stays constant during conjugation. How you extract it depends on the verb group.
Godan stems
For godan verbs, the stem is everything before the final kana. The final kana changes across the five vowel rows during conjugation. For example, 書く (kaku): the stem is 書 (kak-). To form different bases, the final consonant connects with different vowels: kak-a (ない form), kak-i (ます form), kak-u (dictionary), kak-e (conditional/potential), kak-o (volitional).
Ichidan stems
For ichidan verbs, simply remove -ru. That’s it. 食べる → 食べ (tabe-). 見る → 見 (mi-). This stem never changes. Every suffix attaches directly to it.
Irregular stems
する becomes し (shi-) for most forms but has unique changes for certain conjugations. 来る becomes 来 but is read differently depending on the form: き (ki-) for ます form, こ (ko-) for volitional/negative. These must be memorized.
The five bases of godan verbs
Godan verbs are called "five-step" because their ending shifts across five vowel rows. Using 書く as our model: 未然形 (mizenkei) = 書か (kaka-), used for negative and passive. 連用形 (ren’youkei) = 書き (kaki-), used for masu form and compound verbs. 終止形 (shuushikei) = 書く (kaku), the dictionary form. 仮定形 (kateikei) = 書け (kake-), used for conditional and potential. 命令形 (meireikei) = 書け (kake), the imperative. Understanding these five bases is the key to mastering all godan conjugation.
When to use the dictionary form
The dictionary form is not just for dictionaries. It appears in five key contexts in everyday Japanese.
1. Casual conversation
Among friends, family, and people of equal or lower status, dictionary form replaces masu form entirely: 明日何する？(What are you doing tomorrow?) — 映画見る。(Watching a movie.)
2. Before grammatical structures
Many grammar patterns require dictionary form: ～ことができる (can do), ～つもり (intend to), ～前に (before doing), ～と思う (I think I’ll). You cannot use masu form before these.
3. Relative clauses
When a verb modifies a noun, it must be in plain form: 日本語を話す人 (a person who speaks Japanese), 昨日買った本 (the book I bought yesterday).
4. Quoting thoughts and speech
The quotation particle と requires plain form: 行くと言った (said they’d go), 面白いと思う (I think it’s interesting).
5. Written Japanese
Academic papers, news articles, and formal writing use plain form (dictionary form + だ/である), not masu form.
Stem extraction for all three groups
| Verb | Group | Dictionary | Stem | Masu stem |
|---|---|---|---|---|
| 書く | Godan | kaku | kak- | 書き (kaki) |
| 話す | Godan | hanasu | hanas- | 話し (hanashi) |
| 待つ | Godan | matsu | mat- | 待ち (machi) |
| 読む | Godan | yomu | yom- | 読み (yomi) |
| 買う | Godan | kau | ka(w)- | 買い (kai) |
| 食べる | Ichidan | taberu | tabe- | 食べ (tabe) |
| 見る | Ichidan | miru | mi- | 見 (mi) |
| 起きる | Ichidan | okiru | oki- | 起き (oki) |
| する | Irregular | suru | s-/sh- | し (shi) |
| 来る | Irregular | kuru | k- | 来 (ki) |
Example sentences
今日は何もしない。ゲームする。
Kyou wa nani mo shinai. Geemu suru.
I’m not doing anything today. I’m gonna play games.
Casual speech — dictionary form as present tense
日本語を話す人に会いたい。
Nihongo o hanasu hito ni aitai.
I want to meet someone who speaks Japanese.
Dictionary form in relative clause
毎朝6時に起きることにしている。
Maiasa rokuji ni okiru koto ni shite iru.
I’ve made it a habit to wake up at 6 every morning.
Dictionary form before ことにする
寝る前にいつも本を読む。
Neru mae ni itsumo hon o yomu.
I always read a book before sleeping.
Dictionary form before 前に
明日雨が降ると思う。
Ashita ame ga furu to omou.
I think it will rain tomorrow.
Dictionary form before と思う
Common mistakes
日本語を話します人 (hanashimasu hito)
日本語を話す人 (hanasu hito)
Masu form cannot modify nouns. Relative clauses always require plain form (dictionary form or た form).
食べます前に (tabemasu mae ni)
食べる前に (taberu mae ni)
Grammar structures like ～前に, ～ことができる, ～つもり all require dictionary form, never masu form.
行くと言いました → 行きますと言いました
行くと言いました (iku to iimashita)
The quoted verb stays in plain form even when the main verb (言いました) is polite. The と quotation particle demands plain form.
Frequently asked questions
Is the dictionary form the same as "plain form"?
Almost. "Plain form" includes four variants: dictionary form (non-past affirmative), ない form (negative), た form (past), and なかった (past negative). The dictionary form specifically refers to the non-past affirmative (e.g., 食べる). In casual usage, people sometimes say "plain form" when they mean "dictionary form," but technically plain form is the broader category.
Can I use dictionary form with strangers?
Generally no. Using dictionary form with strangers, elders, or in business contexts sounds rude or overly casual in Japanese. Use masu form (polite) instead. However, dictionary form is appropriate in written Japanese (news, academic papers) and when quoting within polite sentences.
Why is the godan stem written with a consonant only (kak-)?
Because the final vowel changes depending on the conjugation: kak-a-nai, kak-i-masu, kak-u, kak-e-ba, kak-o-u. The stem is the consonant that stays constant. For kana-based learners, think of it as the row: ka-行 shifts between か, き, く, け, こ.
What is the stem of 書く?